Problem Statement: How to get a key by its value in a dictionary in Python

Example:

# Given dictionary

employee = {"Sam": 1010, "Bob": 2020, "Rob": 3030} # Some Way to extract the Key 'Bob' using its value 2020

We have a clear idea about the problem now. So without further delay, let us dive into the solutions to our question.

Solution 1: Using dict.items()

Approach: One way to solve our problem and extract the key from a dictionary by its value is to use the dict.items(). The idea here is to create a function  that takes the provided value as an input and compares it to all the values present in the dictionary. When we get the matching value, we simply return the key assigned to the value.

Solution:

# Given dictionary

employee = {"Sam": 1010, "Bob": 2020, "Rob": 3030} # Function that fetches key from value

def get_key(v): for key, value in employee.items(): # return the key which matches the given value if v == value: return key return "The provided key is not present in the dictionary" # Passing the keys to the function

print("Employee ID - 2020 \nName - ", get_key(2020))

Output:

Employee ID - 2020 Name - Bob

Note: dict.items() is a dictionary method in Python that returns a view object. The returned view object contains a list of tuples that comprises the key-value pairs in the dictionary. Any changes made to the dictionary will also be reflected in the view object.

Example: The following example demonstrates how the dict.items() method works.

# Given dictionary

employee = {"Sam": 1010, "Bob": 2020, "Rob": 3030}

item = employee.items()

employee['Tom'] = '4040'

print(item)

Output:

dict_items([('Sam', 1010), ('Bob', 2020), ('Rob', 3030), ('Tom', '4040')])

Solution 2: Using keys(), values() and index()

Approach: Another workaround to solve our problem is to extract the keys and values of the dictionary separately in two different lists with the help of the keys() and values() methods. Then find the index/position of the given value from the list that stores the values with the help of the index() method. Once the index is found, you can easily locate the key corresponding to this index from the list that stores all the keys.

Solution: Please follow the comments within the code to get an insight of the solution.

# Given dictionary

employee = {"Sam": 1010, "Bob": 2020, "Rob": 3030}

# store all the keys in a list

key = list(employee.keys())

# store all the values in another list

val = list(employee.values())

# find the index of the given value (2020 in this case)

loc = val.index(2020)

# Use the index to locate the key

print(key[loc])

Output:

Bob

Note:

• keys() is a dictionary method that returns a view object that contains the keys of the dictionary in a list.
• values() is a dictionary method that returns a view object consisting of the values in the dictionary within a list.
• The index() method is used to return the index of the specified item in a list. The method returns only the first occurrence of the matching item.

Example:

employee = {"Sam": 1010, "Bob": 2020, "Rob": 3030}

li = ['Lion', 'Dog', 'Cat', 'Mouse', 'Dog']

key = list(employee.keys())

val = list(employee.values())

loc = li.index('Dog')

print(f"Keys: {key}")

print(f"Values: {val}")

print(f"Index: {loc}")

Output:

Keys: ['Sam', 'Bob', 'Rob']

Values: [1010, 2020, 3030]

Index: 1

Solution 3: Interchanging the Keys and Values

Approach: The given problem can be resolved using a single line of code. The idea is to use a dictionary comprehension that reverses the keys and values. This means the keys in the original dictionary become the values in the newly created dictionary while the values in the original dictionary become the keys in the newly created dictionary. Once you have interchanged the keys and values, you can simply extract the key by its value.va

Solution:

employee = {"Sam": 1010, "Bob": 2020, "Rob": 3030}

res = dict((val, key) for key, val in employee.items())

print("Original Dictionary: ", employee)

print("Modified Dictionary: ", res)

# using res dictionary to find out the required key from employee dictionary

print(res[2020])

Output:

Original Dictionary: {'Sam': 1010, 'Bob': 2020, 'Rob': 3030}

Modified Dictionary: {1010: 'Sam', 2020: 'Bob', 3030: 'Rob'}

Bob

Explanation:

• employee dictionary has Name and Employee ID as Key-Value pairs.
• res dictionary interchanges the keys and values of the employee dictionary. Therefore, res now has Employee ID and Name as Key-Value pairs.
• Since we need to extract the name corresponding to an Employee ID. We can simply get that from the res dictionary with the help of the key which in this case is the Employee ID.

Solution 4: Using zip()

Considering that the values in the given dictionary are unique, you can solve the problem with a single line of code. The idea is to use the keys() and values() dictionary methods to extract the keys and values from the dictionary and then tie them together with the help of the zip() method to produce a dictionary.

employee = {"Sam": 1010, "Bob": 2020, "Rob": 3030}

name = dict(zip(employee.values(), employee.keys()))[2020]

print(f'Name: {name} \nEmployee ID: 2020')

Output:

Name: Bob Employee ID: 2020

Solution 5: Using Pandas

We can also opt to use the Pandas DataFrame to get the key by its value. In this approach, first, we will convert the given dictionary into a data frame.  Further, we can name the column with the keys as “key” and the columns with the values as “value“. To get the key by the given value, we have to return the value from the ‘key‘ column from the row where the value of the ‘value‘ column is the required value.

Example:

# Importing the pandas module

import pandas as pd # Given dictionary

employee = {"Sam": 1010, "Bob": 2020, "Rob": 3030}

# list to store the keys from the dictionary

key = list(employee.keys())

# list to store the values from the dictionary

val = list(employee.values())

# Converting the dictionary into a dataframe

df = pd.DataFrame({'key': key, 'value': val})

print("The data frame:")

print(df)

# Given Value

v = 2020

print("The given value is", v)

# Searching for the key by the given value

k = (df.key[df.value == v].unique()[0])

print("The key associated with the given value is:", k)

Output:

The data frame: key value

0 Sam 1010

1 Bob 2020

2 Rob 3030

The given value is 2020

The key associated with the given value is: Bob

Note: df.key[df.value == v].unique()[0]) –> We have to use the unique method in this line to avoid the index from getting printed. While using the panda’s data frame, the output is not in the string format, but it is a pandas series object type. Hence, we need to convert it using the unique or sum() method. Without the unique method, the output will also consider the index of the data frame column.

Conclusion

That’s all about how to get a key by the value in the dictionary. I hope you found it helpful. Please stay tuned and subscribe for more interesting tutorials. Happy Learning!

Many factors could lead to the error: ‘pip’ is not recognized as an internal or external command. Two of the most common ones are Python’s or pip’s incorrect installation and lacking path in the system environment variables.

This tutorial deeply explains the concept of environment variables, system paths, and pip’s way of storing packages to enable you to track the source of the error comfortably.

It then takes you through a step-by-step way to solve the error. Apart from Windows, you will see how to solve related errors in Linux. What is more? Read on to find out.

❒What Are Environment Variables?

Understanding environment variables is one the most crucial steps to solving pip’s errors.

A computing environment is a platform consisting of the operating system and the processor. On the other hand, a variable is a place for storing a value. The variable can be binary, text, number, filename, or any other data type. It gets its name during creation and can be displayed, updated, and deleted.

The combination of a computing environment and variable is an environment variable, a dynamic value affecting the behavior of a computer process. A computer process is an instance of a program.

# Determine the value of a variable

echo %VARIABLE% # in Windows

echo $VARIABLE # in Linux # display

%VARIABLE% # in Windows

env # command for printing all environment variables OR

printenv # show a single environment variable in Linux.

Features Of Environment Variables

• They can be created, read, edited, and deleted.
• Each process has its set of environment variables. A newly created process inherits its parent’s same runtime environment.
• Environment variables occur in scripts and the command line.
• Shell scripts and batch files use environment variables to communicate data and processes to child processes or temporarily store data.
• A running process can access the environment variables for configuration reasons.
• A collection of environment variables behave like an associative array, with keys and values in strings.
• Environment variables may differ depending on the operating system.
• Windows stores the default environment variable values in the registry and sets them in the AUTOEXEC.BAT file.

Examples Of Environment Variables

Here are the typical environment variables that interact with pip.

PATH

The path variable lists the directory where your system searches executables. It enables you to view the location of a directory without typing the full path.

In Windows, the path variables are stored in C:\Windows or C:\Windows\System32. In Linux, they originate from the user’s bin or sbin file.

HOME

It shows the default path to the user’s home directory. For instance, HOME//APPDATA stores app settings in Windows. In Linux, the settings are found in HOME/{.App Name}.

In Windows, the misplaced APPDATA lands in the USERPROFILE environment variable, which should instead be used for dialogs to allow a user to choose between folders. LOCALAPPDATA stores local app settings.

TEMP

It stores temporary processes.

Now that you understand how environment variables play a massive in package working, you should find out specific ways to solve pip’s errors.

❒Solution 1: Ensure Pip Is Installed Correctly And Up-to-date

Windows

Pip packages are stored in Python’s installation directory. For instance, installing Python in C:\Python\ stores the default library in C:\Python\Lib\, while the third-party packages reside in C:\Python\Lib\site-packages.

If you install a specific Python version as a stand-alone, pip packages reside in APPDATA.

C:\Users\<username>\AppData\Roaming\Python\Python<version-subversion>\site-packages\ # the version can be 310 for Python 3.10 or 38 for Python 3.8

If you install a pip package that does not use a specific location, it lands in Scripts.

C:\Python310\Scripts\ 

Pip gets installed by default when you install most Python 3 versions. You can confirm the installation by checking the pip’s version or help command.

pip -V

# OR

pip help

You should get pip’s version version, installation folder, and Python version running it.

pip 22.0.4 from C:\Users\<username>\AppData\Local\Programs\Python\Python310\lib\site-packages\pip (python 3.10)

Otherwise, you could get an error,

'pip' is not recognized as an internal or external command

OR

Python is not recognized as an internal or external command, operable program or batch file.

if you try running python.

python

If you run the above commands without seeing Python, pip, or the installed package, you should download Python.

Install pip as a stand-alone package if pip is still unavailable after installing Python. Download get-pip, and run the following command on the command prompt.

python get-pip.py

Lastly, you can upgrade the pip version and check if the error persists.

python -m pip install --upgrade pip

If the problem is still not solved, try adding Python to the system path variable, as explained in solution 2 of this tutorial.

Linux

The usr is one of the most crucial folders in Linux. It stores information like user binaries, libraries, documentation, and header files. It is where packages that pip manages get installed.

Say we want to install Python 3.10 on Ubuntu 20.04. We can do that by downloading Python from the source or using the deadsnakes custom PPA as follows.

# Update the system, ensuring the required packages are installed.

sudo apt update && sudo apt upgrade -y # Install the required dependency needed to add the custom PPAs.

sudo apt install software-properties-common -y # Add the deadsnakes PPA to the list of APT package manager sources.

sudo add-apt-repository ppa:deadsnakes/ppa # Download Python 3.10

sudo apt install python3.10 # Confirm successful installation

python3.10 --version

The next step is to locate pip.

# pip

pip --version

# OR

pip -V

pip list -v # pip3

pip3 -V

pip list -v

Either way, you may get the following errors.

# pip

Command 'pip' not found, but can be installed with:

sudo apt install python3-pip # pip3

Command 'pip3' not found, but can be installed with:

sudo apt install python3-pip

You get a similar error when you try installing a package.

# pip

pip install django

Command 'pip' not found, but can be installed with:

sudo apt install python3-pip # pip3

pip3 install django

Command 'pip3' not found, but can be installed with:

sudo apt install python3-pip

Let’s install pip.

sudo apt install python3-pip

❒Solution 2: Add The Path Of Pip Installation To The PATH System Variable

You can use the terminal or the GUI.

setx PATH "%PATH%;C:\Python<version-subversion>\Scripts" # For example

setx PATH "%PATH%;C:\Python310\Scripts" # for Python 3.10

To use the GUI,

1. copy to the full path of the system variable: C:\<username>\steve\AppData\Local\Programs\Python\Python310\Scripts
2. Type Edit the Environment Variables on the search bar.
3. On the pop-up window, click on the Advanced tab followed by Environment Variables.

4. You are presented with two boxes. Highlight path on the first box followed by the Edit button below the box.

5. Click on New, paste the script path you had copied earlier, followed by OK on the bottommost part of the screen.

Conclusion

You have learned the leading causes of the error, “‘pip’ is not recognized as an internal or external command,” while installing packages and two typical ways to correct it.

You can check whether your installation was successful and whether the pip is updated and lies in the correct path. Otherwise, you can take the most appropriate step, as explained in this tutorial.

Please stay tuned and subscribe for more interesting discussions.

Here is Cazny a project management tool for freelancers and am happy to share it with you. It is a feature-packed, hosted, and ready-to-use software. It enables you to better project management and saves your precious time.

It is an exclusive tool for freelancers to manage the full lifecycle of a project. The proposal, contract, client CRM, project, task, timesheet, invoices, and payment are the broad areas catered to.

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Among all the good things Cazny has, one thing that I wish to highlight is the UI/UX design. All it will take is just 5 minutes to start using it to the fullest of its capability.

A spreadsheet will not help you to scale your business. You start as a freelancer, progress to creating a tiny team, then you graduate to become a freelance agency. You need an all-in-one tool and that is Cazny.

You definitely need a good tool to embark and succeed on this journey. Cazny will be a trustable subordinate for you. It will not be an overhead definitely.

It is brought to you with ritually followed design principles. Best-in-class security, ease of use, and analytical information are core features of Cazny.

Why Cazny?

If you answer “Yes” to any of the below questions, then Cazny is an option for you. If you say “Yes”, multiple times, then it is high time you start using Cazny.

• Are you expecting to manage projects, clients, invoices, and payments in a single place?
• Are you looking for a real-time connector that relates your freelancer’s projects, clients, invoices, and payments?
• Do you expect to hire a flawless assistant to manage your running projects and tasks?
• Do you have all your business data spread over assorted spreadsheets?
• Do you frequently smash your head to get basic stats about the currently running projects?
• Do you still use the age-old practice of unorganized email threads to manage projects?
• Do you depend on anybody to know the open tasks of your projects?
• Does it take an hour to get your income for the financial year?
• Are you looking for a graphical presentation of your payment statistics?
• Are you using multiple online software for client records, project-task management, invoicing, etc?

All the above questions have one magic answer, that is, Cazny. Go deeper into this article to see what is Cazny and how it is going to play a major role in your business.

How did it evolve?

When there is a boom in the number of running projects, management itself becomes a big project. My freelancing business is getting better by every day. As a freelancer, I struggled to deal with management work in parallel with the development and delivery.

We built software to help manage my day-to-day administrative activities. It got me out of this management struggle and saved me precious billable hours. It not only has relieved but also helped to scale up my freelance business.

Before Cazny I used to accept only a couple of projects in parallel. Now I have a team and do 10+ projects in parallel. See, what my clients are saying about my work. It became possible with the help of Cazny.

What is inside Cazny?

I have written more than 100 ‘what is inside’ tables of content for different products and projects. But here it will be a huge list if I add bullets for everything inside Cazny.

Let me present you a shrunk version of the list with key functionality.

Key features

1. One unified software for all the needs of a freelancer for management
2. Client CRM
3. Flexible task management
4. Timesheet log
5. Income analytics
6. Invoice generation
7. Sales automation and payment tracking

Other features

1. Custom fields
2. Multi-language
3. Simple search and advanced filters
4. Connecting entities for relevancy
5. Data security

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Free signup and easy membership creation

Cazny allows you to signup for free with unlimited access to all features.

Members can subscribe at any moment within the trial period.

Project management with client CRM and tasks

This section describes the heart of this project management tool.

The complete tool goes around with these three core entities client, project, and task. The other entities of the project management tool are dependent on these primary assets.

Project scheduling with timesheet

Timesheet log is a critical component of a freelancer’s earnings. In my earlier days of being a freelancer, I lost income because of unorganized timesheet records.

All we need is a good tool and basic discipline. Cazny’s timesheet module is intuitive and easy to record task activities.

Invoice for payments

As a freelancer, you can survive without a management tool for all the features but one. A professional invoice is a key to building your brand as a freelancer and continuing business with a client.

Cazny has an intuitive, WYSIWYG editor for generating invoices. It populates and drops down the dependent client/project data to generate data.

It is highly customizable to suit your business. It has more options that are too user-friendly in the context of invoice generation. Example,

1. Preview invoice.
2. Generate and download PDF.
3. Share invoice to a client with just a click of a button.
4. Email invoice from within the tool.

Sales automation and payment tracking

Payments tracking at their best with Cazny both by data tables and graphs. Comparatively, the payment graph view helps freelancers to have a quick bird’s eye view of the income.

This is one of my long-time issues of searching for payment data manually on emails to calculate the income at the stage. Combined with filter, data table and charts, income analysis is just a breeze with Cazny.

More features of Cazny

All functionality uses rich features to provide a good user experience.

Custom fields

For each freelancer, the client, project, and task have unique columns. This project management tool is designed with minimal and most wanted fields.

If you need additional fields, this feature helps you to add more. It contains add, edit, and remove options on each entity.

Multi-language implementation

The multi-language implementation is made across the site. It is configurable by every member to suit your preference. For public pages, the language can be specified by choosing the option in the header dropdown.

The member can choose their language on the account settings page. Based on this selection, the application framework loads the content. Now you can manage your projects in your own native language.

Common search and criteria based filter

Cazny provides an efficient search feature. It has two types of filters to search among the project management tool.

1. A simple keyword-based common search filter.
2. A Field-specific criteria-based filter form.

Search is very quick and seamless.

Connecting entities for relevancy

It is all about loading relevant data based on the parent entity. This is to load,

• Clients by member
• Projects by clients
• Tasks by projects
• Timesheet by tasks
• Invoice to clients
• Payments by project, invoices

Data security

It assures for security and protection of member-submitted data. It follows global norms and state-of-the-art tech to protect your data. Architected and developed be members with good experience. Also, a third-party security audit is conducted to ascertain the quality of the software.

Conclusion

As a seasoned freelancer with an agency, we built Cazny for our internal purposes. This has helped us to scale up our business by freeing up our valuable time from administrative activities.

We are launching the tool to you in the belief that it will save your precious time and allow you to focus more on billable hours. Please leave your feedback in the comments section.

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